Zika Most Damaging During Rapid Brain Growth

JUPITER, Florida, October 17, 2016 (ENS) – In new research that could help eliminate the tragic birth defects caused by the Zika virus, scientists from the Florida campus of The Scripps Research Institute, TSRI, have pinpointed how the virus attacks the brains of newborns, information that could accelerate the development of treatments.

The study, led by TSRI Associate Professors Hyeryun Choe and Damon Page, is published in the journal “Nature Scientific Reports.”

In the new study, the scientists observed the virus’s effects in animal models at two different points – during early postnatal development, when the brain is growing rapidly, and at weaning, when the brain has reached adult size.

Held by Alison Stillwell Young, Kokuvi is a student at the Volta School for the Mentally Challenged in Gbi-Kledjo, Volta Region, Ghana; he is a 17-year-old with microcephaly. (Photo courtesy Alison Stillwell Young)

“In early postnatal Zika-infected models some brain areas and cell types showed particularly large increases in apoptosis [programmed cell death] that we did not observe in older animals,” Choe said.

The findings expand the current knowledge of cell types vulnerable to the effects of Zika infection to include not only neuron progenitor cells, but also post-mitotic neurons that have finished dividing but are still are undergoing rapid increases in cell size, the authors say.

These results are consistent with the theory that periods of rapid brain growth are especially susceptible to the damaging neurodevelopmental effects of Zika infection.

“An interesting aspect of the study is the comparison of the two time points,” Page said. “There is neural cell death at both times, but it’s much greater when the brain is growing rapidly.”

“We can take advantage of this strong effect to test potential treatments and to understand whether some genetic backgrounds may confer enhanced susceptibility or resilience to Zika-induced microcephaly,” said Page.

Zika virus was first isolated in rhesus macaque monkeys in Uganda in 1947. Transmitted by infected Aedes species mosquito mosquitos, it is related to several other human pathogens, including West Nile virus, dengue, Japanese encephalitis virus and yellow fever.

These mosquitoes bite during the day and night. Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects.

There is no vaccine or medicine for Zika.

Local mosquito-borne Zika virus transmission has been reported in the continental United States, in Miami-Dade County, Florida.

As widely reported, the 2015 Zika epidemic in Brazil coincided with a dramatic increase in cases of microcephaly in newborns, a disease that results in babies with small heads and brain damage.

“Our findings establish a valuable model to investigate the mechanisms that underlie the horrific birth defects associated with Zika infection,” said TSRI Graduate Student Wen-Chin Huang, the first author of the study.

The team is continuing to build on this study to better understand and combat the virus.

In addition to Choe, Page and Huang, other authors of the study, “Zika Virus Infection During the Period Of Maximal Brain Growth Causes Microcephaly and Corticospinal Neuron Apoptosis in Wild Type Mice,” include Rachy Abraham and Byoung-Shik Shim of TSRI.

The study was supported by the National Institutes of Health and by Nancy Lurie Marks.

The Scripps Research Institute is one of the world’s largest independent, not-for-profit organizations focusing on research in the biomedical sciences. TSRI is internationally recognized for its role in laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases.